"I am sickened at the extent and pervasiveness of dishonesty and misdirection by individuals in the highest office of the land, including the President," Romney, Utah's junior senator, said in a release. "I am also appalled that, among other things, fellow citizens working in a campaign for president welcomed help from Russia - including information that had been illegally obtained; that none of them acted to inform American law enforcement; and that the campaign chairman was actively promoting Russian interests in Ukraine."

The report highlighted instances in which Trump tried to fire Mueller, including asking White House counsel Don McGahn to do so. He did not, and the report states the administration then tried to cover the request up.

Romney's statement referred to Trump's infamous July 2016 press conference inviting the Russians to find Hillary Clinton's emails, after which future National Security Adviser Michael Flynn contacted multiple people about finding the "missing" Clinton emails from her personal server, according to the report. Romney also referred to campaign chairman Paul Manafort in his statement, who met with representatives from Ukraine and has since been sentenced to four years jail time.

Very few Republicans have spoken out against the revelations in the Mueller report. Trump himself repeatedly declared he was absolved of all accusations in the "witch hunt," even though the report did not exonerate him of obstruction. Attorney General William Barr instead declared the information in the report did not rise to the level of criminal prosecution.

"I think he has every right to feel good about what we've heard today," McConnell told reporters Thursday, referring to Trump.

Romney's relationship with the president has see-sawed between open criticism and reluctant support.

Trump supported Romney during his midterm election bid for senator. But the former presidential candidate, who Trump has called a "stiff" and "choke artist" in the past, followed his election victory with a scathing column in The Washington Post in January.

Romney wrote, "His conduct over the past two years, particularly his actions this month, is evidence that the president has not risen to the mantle of the office. A president should demonstrate the essential qualities of honesty and integrity, and elevate the national discourse with comity and mutual respect."

Trump responded on Twitter, at the time, saying, "Would much prefer that Mitt focus on Border Security and so many other things where he can be helpful. I won big, and he didn't."

Romney finished his statement Friday with a call to return to principles the country was built on.

"Reading the report is a sobering revelation of how far we have strayed from the aspirations and principles of the founders," he said.